Single big backfire, rough/no idle

[RavenTBK]

Okay.. I messed up. Yesterday, after I put the engine back into the Brat, I connected up the plug wires backwards with regards to distributor orientation. I had a brainfart and thought that #1 was the front of the dizzy.

 

Anywho, I quickly realized that this wasnt the case. After a few revolutions with the starter, I had an absolute serious backfire...BOOM!... blew both breather lines off the valve covers, and shot the oil dipstick across the shop. I mean this one was bad. Since then, theres been a no idle/lean situation going on. At cruising revs, no problem.. but as the revs drop below 2000, its like crap leans out and wants to stall. Gotta keep feathering the throttle to keep it running.

 

Today, I managed to reconnect all the offending vac lines that were blown off and tore the weber apart to inspect its gaskets and whatnot for possible damage, and I blew through the passages with the air gun just to make sure nothing fresh was blocking a passage way. I also fiddled with the timing a bit just for giggles.

 

I've managed to get it to idle, however rough. The timing is adjusted so far out it was pinging like hell on the testdrive...but it barely idles..which is better than what it did before.

 

My mechanic buddy believes the serious backfire (which he was there to witness) blew an intake gasket..which is causing the lean style non-idle. He's wanting me to tear it down and install a new intake gasket tomorrow. I just wanted to post up for thoughts/opinions on the validity of his prediction.

 

With all the headaches I've experienced over the last several months, I'm beginning to think (again!) that it would just be easier to swap in an EJ.

 

PS: I've also managed to pick up a couple of fresh oil leaks from areas where they didnt exist before... heh.. I blew it up. I'm probably going to have to pull the engine out again, and take the Brat off of DD duty again for the next year while I try to gather up the funding to fix this mess. :-\

 

Miles needs to take his traveling mechanic self and come on down this way.

[NorthWet]

My vote goes for a vacuum leak. The intake gaskets are a likely suspect. Good luck!

[MorganM]

Shot the dips stick accross the shop! WAHOOOO! Did you both look at eachother like ?

 

Might have screwed up that carb if the back fire came up through the intake. Maybe a carb base gasket? INtake gasket (tho you'd prolly get some coolant leakage with that also)? Possibly just cracked a vacume line that looked connected still? Dizzy still maybe a tooth off?

 

The fact it runs okay at higher RPMs is promising Pull your spark plugs and see just how lean it's getting!

 

Good luck Raven

[RavenTBK]

Hmm.. I havent done anything to it, and it automagically healed itself. Idles about as fine as it can with an untuned carb, and revs and cruises nicely.

 

I adjusted the dizzy a bit, and have gotten rid of the ping.

 

And Morgan.. it wasnt a "look at each other like :eek:" thing. It was more of both of us dropping to the shop floor. "Hit the deck!" kind of thing.

 

But I dont get it.. I didnt do a dang thing, and its fine again. One thing thats strange is I've got high vacuum now. I mean perfect, new engine style high vacuum. Remove the oil cap and it sucks and dies.

 

Only downside is my belt squeal noise has returned.. which is why I pulled the engine to check out the clutch/bearings in the first place.

 

Tomorrow I'll retune the carby and start poking around with the stethoscope to find my squeal. *shrugs*